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An iteration-free approach to excitation harmonization
No full textSinusoidal excitation is particularly popular for testing structures in the nonlinear regime. Due to the nonlinear behavior and the inevitable feedback of the structure on the exciter, higher harmonics in the applied excitation are generated. This is undesired, because the acquired response may deviate substantially from that of the structure under purely sinusoidal excitation, in particular if one of the higher harmonics engages into resonance. We present a new approach to suppress those higher excitation harmonics and thus the unwanted exciter-structure interaction: Higher harmonics are added to the voltage input to the shaker whose Fourier coefficients are adjusted via feedback control until the excitation is purely sinusoidal. The stability of this method is analyzed for a simplified model; the resulting closed-form expressions are useful, among others, to select an appropriate exciter configuration, including the drive point. A practical, model-free procedure for the control design is suggested. The proposed method is validated in virtual and physical experiments of internally resonant structures, in the two common configurations of force excitation via a stinger and base excitation. Excellent performance is achieved when simply using the same control gains for all harmonics, throughout the tested range of amplitudes and frequencies, even in the strongly nonlinear regime. Compared to the iterative state of the art, it is found that the proposed method is simpler to implement, enables faster testing and it is easy to achieve a lower harmonic distortion
Detection of myocardial deformation patterns and prognostic value of routine echocardiographic parameters in patients with cardiac sarcoidosis versus extracardiac sarcoidosis: a systematic review and meta-analysis
No full textBackground: Sarcoidosis is a multisystem disorder characterized by non-caseating granulomas in various organs. While cardiac sarcoidosis (CS) is clinically rare, it has significant implications, including heart failure, ventricular arrhythmias, and sudden cardiac death. Speckle-tracking echocardiography has emerged as a promising tool for detecting subclinical myocardial dysfunction, which is cost-efficient and readily available. This meta-analysis aims to evaluate differences in functional echocardiographic parameters between patients with CS and extracardiac sarcoidosis (ECS) to improve early recognition and management. Methods: A comprehensive search of major bibliographic databases was conducted to identify studies up to December 2024. Mean differences (MDs) with 95% CIs were pooled using the inverse-variance random-effect model. Results: Seven studies with 478 patients with sarcoidosis (CS: 159 and ECS: 319) were included. Patients with CS had a significant reduction in left ventricular global longitudinal strain (MD: −2.73; 95% CI: −4.09, −1.38; p < 0.0001) and tricuspid annular plane systolic excursion (MD: −0.59; 95% CI: −1.12, −0.05; p = 0.03) compared to patients with ECS. No significant differences in the LV global circumferential strain, interventricular septum thickness, left ventricular ejection fraction, E/A ratio, E/E’ ratio, LV end-diastolic diameter, and LV end-systolic diameter were noted. Conclusions: LV GLS and TAPSE are promising parameters for the early detection of cardiac involvement in sarcoidosis, with significant prognostic implications. Although STE provides a cost-effective and accessible alternative to CMR and FDG-PET, further research is needed to standardize its use and validate diagnostic cut-offs
Dietary nitrate supplementation enhances exercise capacity in WHO Group 3 pulmonary hypertension: a double-blind, placebo-controlled, randomised crossover study (EDEN-OX2)
No full textDietary nitrate supplementation, which improves skeletal muscle oxygen utilisation, vascular endothelial function and exercise capacity in people with chronic obstructive pulmonary disease, may benefit other lung conditions. In a double-blind, placebo-controlled, crossover study, in 19 adults with Group 3 pulmonary hypertension who desaturated during exercise, 140 mL of nitrate-rich beetroot juice improved endurance shuttle walk time compared with nitrate-depleted beetroot juice placebo (median (IQR) ESWT NR-BRJ 197 (140–273) s vs PL-BRJ 174 (107–229) s; median difference (MD) (95% CI) 30 (6.19 to 91.07) s, p=0.0281), endothelial function, flow-mediated dilatation (+3.40±5.47% vs −1.33±4.78; MD (95% CI) 4.73 (1.44 to 8.02), p=0.007) and lowered mean arterial blood pressure (−3.9 (−7.4 to −0.4) mm Hg, p=0.028)
TockyPrep: data preprocessing methods for flow cytometric fluorescent timer analysis
No full textBackground:
Fluorescent Timer proteins, which display time-dependent changes in their emission spectra, are invaluable for analyzing the temporal dynamics of cellular events at the single-cell level. We previously developed the Timer-of-cell-kinetics-and-activity (Tocky) tools, utilizing a specific Timer protein, Fast-FT, to monitor temporal changes in cellular activities. Despite their potential, the analysis of Timer fluorescence in flow cytometry is frequently compromised by variability in instrument settings and the absence of standardized preprocessing methods. The development and implementation of effective data preprocessing methods remain to be achieved.
Results:
In this study, we introduce the R package that automates the data preprocessing of Timer fluorescence data from flow cytometry experiments for quantitative analysis at single-cell level. Our aim is to standardize Timer data analysis to enhance reproducibility and accuracy across different experimental setups. The package includes a trigonometric transformation method to elucidate the dynamics of Fluorescent Timer proteins. We have identified the normalization of immature and mature Timer fluorescence data as essential for robust analysis, clarifying how this normalization affects the analysis of Timer maturation. These preprocessing methods are all encapsulated within the TockyPrep package.
Conclusions:
TockyPrep is available for distribution via GitHub at https://github.com/MonoTockyLab/TockyPrep, providing tools for data preprocessing and basic visualization of Timer fluorescence data. This toolkit is expected to enhance the utility of experimental systems utilizing Fluorescent Timer proteins, including the Tocky tools
Stability of two flowing coaxial ferrofluid annuli
No full textTwo concentric ferrofluid annuli fill the gap between two concentric cylinders. In a stationary state without magnetic field, the interface between the fluids is unstable to
surface tension. However, this instability can be controlled either by axial motion if the fluids have different viscosity, or by passing a current down the inner cylinder if the inner
fluid has a higher magnetic susceptibility. If the susceptibilities differ, an axial magnetic field may also grant stability to all but the longest wavelengths. Each of these mechanisms can, however, give rise to other instabilities. This paper investigates the linear stability to arbitrary disturbances of the combination of shear and magnetic effects
NURBS-enhanced finite element spatial discretisation methods for the steady-state multigroup neutron diffusion equation
No full textThe NURBS-enhanced finite element method (NEFEM) is a recent innovation in spatial discretisation methods. The NEFEM combines the conventional FEM with computer-aided geometric design (CAGD) boundary representation (B-rep) approaches based upon Non-Uniform Rational B-spline (NURBS) geometrical representations of the computational domain. The aim of the NEFEM is to streamline the CAGD to computer-aided engineering (CAE) modelling and simulation (M&S) pipeline and provide improved geometrical representations of the underlying curvilinear geometry in nuclear reactor physics and reactor shielding simulations. This eliminates the requirement for local modifications to the underlying computational mesh to preserve the surface areas and volumes of curvilinear geometrical features within the computational domain. Such local mesh modifications are required, within conventional isoparametric Lagrangian FEM approaches, to preserve fissile mass and neutron leakage within curvilinear geometrical and computational domains.
This paper presents the application of the NEFEM to the multigroup neutron diffusion equation (NDE) for three nuclear reactor physics benchmark verification test cases. A further method of manufactured solution (MMS) benchmark verification test case is used to establish the order of convergence of the NEFEM compared to the FEM for both linear and quadratic elements. In addition, an analytical Wigner–Seitz pincell problem is used to further investigate the accuracy of the NEFEM. The results from these benchmark verification test cases demonstrate that the NEFEM yields improved numerical accuracy compared to the conventional FEM. This improved numerical accuracy is primarily achieved through the improved geometrical representation of curvilinear geometries. While the NURBS-enhancement of elements necessitates a small increase to the pre-processing time associated with the method, the increased accuracy of the NEFEM allows it to achieve competitive computational solution times compared to the standard Lagrangian FEM
Disease and economic burden of COVID-19 in the prevaccine era in a fragmented health system: the Argentine case
No full textObjectives
The impact of COVID-19 in Argentina’s health and economic outcomes before the implementation of the national vaccination plan has not been fully characterized. This study aimed to estimate the health and economic burden of COVID-19 in the adult population in Argentina.
Methods
We conducted a retrospective observational study using a national COVID-19 surveillance data set to assess (1) clinical burden, including incidence rates, mortality rates, and patterns of hospitalization categorized by severity based on the World Health Organization criteria; (2) economic burden; and (3) years of life lost. The cost of illness analysis was used to estimate the cost per patient with COVID-19, expressed in 2023 US dollars (1370 million, ranging from 791 in critical cases. Concerning the health sectors, a higher total cost is observed in the social security sector, accounting for nearly 51% of the total costs, mainly because it has the highest rate of health coverage.
Conclusions
Before the vaccines were widely used, COVID-19 significantly strained Argentina’s public health and economy. These discoveries can aid policy makers in making well-informed choices and distributing resources efficiently to enhance future national strategies concerning surveillance, prevention, treatment, and potential long-term impacts on community health
Decarbonising heating and cooling: barriers and opportunities facing aquifer thermal energy storage in the United Kingdom
No full textAquifer thermal energy storage (ATES) is a shallow geothermal technology which can contribute to heating and cooling decarbonisation. The low global deployment of ATES does not match its technical potential. Understanding relevant societal challenges and opportunities is crucial for scaling up ATES deployment. Here, we draw upon a Responsible Innovation (RI) framework to assess the social desirability, opportunities, and limitations applying to wider adoption of ATES in the United Kingdom. We focus on the RI dimensions of anticipation, reflection, inclusion, and responsiveness, and extend the framework to incorporate ethics and frugality. We use information from 14 semi-structured interviews conducted with a representative set of stakeholders associated with ATES, focusing on the Greater Manchester Metropolitan area, a region with significant potential for ATES development. Our results highlight the multifaceted benefits of ATES deployment for the local economy, environment, and energy efficiency, alongside the associated risks. We identify barriers to deploying ATES including a lack of sector-specific regulations, licensing and infrastructure complexities, and uncertainties. To facilitate wider ATES uptake, we suggest focusing on improving market awareness, promoting industry-specific education and knowledge sharing, enabling stakeholder engagement through government initiatives, leveraging stakeholders' collective expertise, as well as developing tailored legislative and regulatory measures to uphold national ATES standards. Central to our findings is the emphasis on value-inclusive design of ATES systems, aligning with social desirability and local priorities such as affordability, safety, reliability, inclusivity, responsiveness, and sustainability
A universal creep model for polymers considering void evolution
No full textCreep behavior in polymers has posed a significant challenge across various industries, yet no theoretical model exists to fully describe their complete three-stage creep process. This paper, for the first time, develops a universal model capable of describing three stages of polymer creep. The model's development is made possible considering void nucleation and evolution during polymer creep, supported by molecular-scale modelling and observations. It provides a precise definition of the start and end times for each creep stage, a milestone not previously achieved. Validation of the model was conducted through creep tests on epoxy resin under different stress levels and temperatures, supplemented by comparisons with experimental data from the literature. The findings show that creep properties, such as creep failure time and minimum creep rate, exhibit an exponential relationship with stress. The model identifies the maximum creep damage (measured by the area fraction of the void in a cross section) for epoxy as 0.15, independent of temperature, with ∼90 % of damage occurring in the tertiary stage. Additionally, the ASTM D 2990 formula tends to overestimate creep failure time, with greater overestimations at lower stress levels—approximately 10 % for a 10-year failure time. This model represents a major advancement, offering the ability to predict the complete three-stage creep failure of any polymer under varying stress and temperature conditions. It provides a critical tool for engineers to reliably predict polymer creep behavior and prevent failure, addressing a long-standing challenge in polymer research and applications
Lifetime financial analysis of a model predictive control retrofit for integrated PV-battery systems in commercial buildings
No full textAs electrical grids decarbonise, the need for flexible, real-time energy management systems becomes crucial to handle the variability of renewable sources. This paper investigates the lifetime performance of a commercial PV-battery system under three potential control approaches. Two rule-based controllers and one economic MPC approach are simulated over the lifetime of the battery, considering both the upfront capital and ongoing operational costs. Under the nominal rule-based control, installing the battery system saves 2.9% in operational costs per year. An informed rule-based schedule was then created, based on observing the typical PV and building loads and electricity price dynamics, increasing savings to 4.3%. These additional savings can be realised without any additional capital or operational investment. A supervisory MPC approach is integrated with the existing system control, requiring an upfront investment of 5.89k/yr. Accounting for these additional costs, net operational savings increase to 6% compared to the baseline operation without a battery system, while also reducing carbon emissions by 9.8%. MPC savings increase to 13.2% when considering the volatile electricity prices seen during the 2022 energy crisis. Despite these encouraging savings, current battery systems remain financially unattractive due to their high upfront cost, and all three control scenarios result in a negative NPV. A sensitivity analysis demonstrates that optimal sizing of batteries and reductions in their cost are the most significant factors when evaluating the lifetime performance of PV-battery systems